In the photographic art color images are formed by exposing a light sensitive silver halide photographic element to actinic radiation, followed by processing in which an oxidized aromatic primary amine color developing agent is reacted with a dye-forming coupler to form yellow, magenta and cyan image dyes in the element.
Known magenta dye-forming couplers include heterocyclic nitrogen compounds such as pyrazolones, pyrazolobenzimidazoles, pyrazolotriazoles and indazolones. Known cyan dye-forming couplers include phenols and naphthols. More recently, some heterocyclic nitrogen compounds have been described as cyan dye-forming couplers. These include the imidazopyrazoles, pyrazolotriazoles and imidazoimidazoles described in U.S. Pat. Nos. 4,728,598, 5,206,130, 4,873,183, 4,916,051 and 5,215,871 and in Japanese Published Patent Applications 01/028638, 02/188749, 04/172447, 04/190348 and 04/194847.
Image dyes in photographic elements should have desired hues and good stability, i.e., they should have little or no fading or discoloration under storage in the dark or when exposed to light. The couplers that provide these dyes should have good coupling efficiency and lead to dye images with good contrast, high density in areas of maximum exposure and low density in minimum exposures areas.
The cyan image dyes formed by phenol or naphthol couplers have desirable spectral absorption characteristics, but their stability is not as great as would be desired. Some cyan image dyes formed from heterocyclic nitrogen couplers have improved stability characteristics, but the spectral absorption characteristic of the dye and the coupling efficiency of the coupler are not as good as would be desired. Thus, it would be desirable to have heterocyclic nitrogen cyan dye forming couplers with good coupling efficiency that provides dyes having desirable spectral absorption characteristics.